TS licensing server 2012 won't issue license

Hi,

I installed a TS server 2012 and licensing server on a Hyper-v VM.  After configuring licensing server , it successful issued to three users, but failed for the rest users, also no issuing record on RD licensing manager except the first three users.  I had event  Terminal Services-Licensing 4105. I run RD licensing diagnose, but didn't report any errors. Please help!!!!!

Thanks

Eric